Some foreign person telling me that my internet was not secure and their technicians were going to help me sort it out. Hung up on them.

I have a policy that if the phone call registers as unknown, I do not answer the phone. If a message is left, then I call message bank and identify if the call is genuine and if so, respond. A scam call can be identified by the caller not bothering to leave a message. Then I add their phone number to my phone list and then block the scammer's phone number. If they call again, their call goes straight to message bank without any audible ring tone.

Just say, "Just A Moment Please, I'll Put You Through To The Person Who Handles It."
Then, hold the phone near the Microwave, press 3 Digits and the Press STOP/CLEAR.
Then (in a Computer Type Voice) say, "Transmitting Virus To Caller Now!", and Quickly Press 4 or 5 Digits and then Press STOP.